An easy to control all-metal in-line-series ohmic RF MEMS switch

Copyright @ 2010 Springer-VerlagThe analysis, design and simulation of a novel easy to control all-metal in-line-series ohmic RF MEMS switch is presented, for applications where the operating frequency ranges from DC to 4 GHz. The proposed switch, due to its unique shape and size, assures high isolation and great linearity fulfilling the necessary requirements as concerns loss, power handling and power consumption. Simplicity has been set as the key success factor implying robustness and high fabrication yield. On the other hand, the specially designed cantilever-shape (hammerhead) allows distributed actuation force ensuring high controllability as well as reliability making the presented RF MEMS switch one of its kind

High-resolution Velocity Fields of Low-mass Disk Galaxies. I. CO Observations

This paper is the first in a series whose aim is to examine the relative distributions of dark and baryonic matter as a function of star formation history in a representative sample of low-mass disk galaxies. In this paper, we present high-resolution 12 CO(j=1→0) interferometry for a sample of 26 nearby dwarf galaxies that were obtained from the Combined Array for Research in Millimeter-wave Astronomy (CARMA). Among these 26 galaxies, 14 have good CO detections, including 6 galaxies previously detected in single-dish CO measurements and 8 newly detected ones. We find a linear correlation between the CO flux and the mid- and far-IR flux from the WISE and IRAS catalogs. Compared to the far-IR flux, the mid-IR flux may be a better indication of whether a galaxy contains sufficient CO for detection at the level of instrument sensitivity of CARMA. This correlation might prove to be useful in future studies to help choosing other CO targets for observation. The median molecular mass (including helium) of our galaxies is 2.8×10 8 M⊙, which is consistent with past observations for dwarf galaxies. The molecular content is weakly correlated with the dynamical mass, r-band luminosity and size of the galaxies. The median ratios of molecular mass versus dynamical mass and molecular mass versus r-band luminosity are M mol M dyn ≈ 0.035 and M mol L r ≈ 0.078M⊙ L r , ⊙, respectively, which are also consistent with past observations for dwarf galaxies

Resolved Multi-element Stellar Chemical Abundances in the Brightest Quiescent Galaxy at z ∼ 2

Measuring the chemical composition of galaxies is crucial to our understanding of galaxy formation and evolution models. However, such measurements are extremely challenging for quiescent galaxies at high redshifts, which have faint stellar continua and compact sizes, making it difficult to detect absorption lines and nearly impossible to spatially resolve them. Gravitational lensing offers the opportunity to study these galaxies with detailed spectroscopy that can be spatially resolved. In this work, we analyze deep spectra of MRG-M0138, a lensed quiescent galaxy at z = 1.98, which is the brightest of its kind, with an H-band magnitude of 17.1. Taking advantage of full spectral fitting, we measure [Mg/Fe] = 0.51 ± 0.05, [Fe/H] = 0.26 ± 0.04, and, for the first time, the stellar abundances of six other elements in this galaxy. We further constrained, also for the first time in a z ~ 2 galaxy, radial gradients in stellar age, [Fe/H], and [Mg/Fe]. We detect no gradient in age or [Mg/Fe] and a slightly negative gradient in [Fe/H], which has a slope comparable to that seen in local early-type galaxies. Our measurements show that not only is MRG-M0138 very Mg-enhanced compared to the centers of local massive early-type galaxies, it is also very iron rich. These dissimilar abundances suggest that even the inner regions of massive galaxies have experienced significant mixing of stars in mergers, in contrast to a purely inside-out growth model. The abundance pattern observed in MRG-M0138 challenges simple galactic chemical evolution models that vary only the star formation timescale and shows the need for more elaborate models

High-resolution Velocity Fields of Low-mass Disk Galaxies. I. CO Observations

This paper is the first in a series whose aim is to examine the relative distributions of dark and baryonic matter as a function of star formation history in a representative sample of low-mass disk galaxies. In this paper, we present high-resolution 12 CO(j=1→0) interferometry for a sample of 26 nearby dwarf galaxies that were obtained from the Combined Array for Research in Millimeter-wave Astronomy (CARMA). Among these 26 galaxies, 14 have good CO detections, including 6 galaxies previously detected in single-dish CO measurements and 8 newly detected ones. We find a linear correlation between the CO flux and the mid- and far-IR flux from the WISE and IRAS catalogs. Compared to the far-IR flux, the mid-IR flux may be a better indication of whether a galaxy contains sufficient CO for detection at the level of instrument sensitivity of CARMA. This correlation might prove to be useful in future studies to help choosing other CO targets for observation. The median molecular mass (including helium) of our galaxies is 2.8×10 8 M⊙, which is consistent with past observations for dwarf galaxies. The molecular content is weakly correlated with the dynamical mass, r-band luminosity and size of the galaxies. The median ratios of molecular mass versus dynamical mass and molecular mass versus r-band luminosity are M mol M dyn ≈ 0.035 and M mol L r ≈ 0.078M⊙ L r , ⊙, respectively, which are also consistent with past observations for dwarf galaxies

MOSFIRE Spectroscopy of Quiescent Galaxies at 1.5 < z < 2.5. II - Star Formation Histories and Galaxy Quenching

We investigate the stellar populations for a sample of 24 quiescent galaxies at 1.5 < z < 2.5 using deep rest-frame optical spectra obtained with Keck MOSFIRE. By fitting templates simultaneously to the spectroscopic and photometric data, and exploring a variety of star formation histories, we obtain robust measurements of median stellar ages and residual levels of star formation. After subtracting the stellar templates, the stacked spectrum reveals the Halpha and [NII] emission lines, providing an upper limit on the ongoing star formation rate of 0.9 +/- 0.1 Msun/yr. By combining the MOSFIRE data to our sample of Keck LRIS spectra at lower redshift, we analyze in a consistent manner the quiescent population at 1 < z < 2.5. We find a tight relation (with a scatter of 0.13 dex) between the stellar age and the rest-frame U-V and V-J colors, which can be used to estimate the age of quiescent galaxies given their colors. Applying this age--color relation to large, photometric samples, we are able to model the number density evolution for quiescent galaxies of various ages. We find evidence for two distinct quenching paths: a fast quenching that produces compact post-starburst systems, and a slow quenching of larger galaxies. Fast quenching accounts for about a fifth of the growth of the red sequence at z~1.4, and half at z~2.2. We conclude that fast quenching is triggered by dramatic events such as gas-rich mergers, while slow quenching is likely caused by a different physical mechanism

Stellar populations from spectroscopy of a large sample of quiescent galaxies at z > 1: Measuring the contribution of progenitor bias to early size growth

We analyze the stellar populations of a sample of 62 massive (log Mstar/Msun > 10.7) galaxies in the redshift range 1 < z < 1.6, with the main goal of investigating the role of recent quenching in the size growth of quiescent galaxies. We demonstrate that our sample is not biased toward bright, compact, or young galaxies, and thus is representative of the overall quiescent population. Our high signal-to-noise ratio Keck LRIS spectra probe the rest-frame Balmer break region which contains important absorption line diagnostics of recent star formation activity. We obtain improved measures of the various stellar population parameters, including the star-formation timescale tau, age and dust extinction, by fitting templates jointly to both our spectroscopic and broad-band photometric data. We identify which quiescent galaxies were recently quenched and backtrack their individual evolving trajectories on the UVJ color-color plane finding evidence for two distinct quenching routes. By using sizes measured in the previous paper of this series, we confirm that the largest galaxies are indeed among the youngest at a given redshift. This is consistent with some contribution to the apparent growth from recent arrivals, an effect often called progenitor bias. However, we calculate that recently-quenched objects can only be responsible for about half the increase in average size of quiescent galaxies over a 1.5 Gyr period, corresponding to the redshift interval 1.25 < z < 2. The remainder of the observed size evolution arises from a genuine growth of long-standing quiescent galaxies

Characteristics of events in which police responded to overdoses: an examination of incident reports in Rhode Island

Background: Narrow or non-existent Good Samaritan Law protections and harsh drug selling statutes in the USA have been shown to deter bystanders from seeking medical assistance for overdoses. Additionally, little is known about the actions that police take when responding to overdose events. The objectives of this study were to assess the prevalence and correlates of naloxone administration by police, as well as to examine overdose events where arrests were made and those in which the person who overdosed was described as combative. Methods: We analyzed incident reports of police responding to an overdose between September 1, 2019, and August 31, 2020 (i.e., 6 months prior to and during the COVID-19 pandemic), from a city in Rhode Island. We examined characteristics of incidents, as well as individual characteristics of the person who overdosed. Correlates of police naloxone administration were assessed using Wilcoxon rank sum tests and Fisher’s exact tests, and we examined incidents where arrests occurred and incidents in which the person who overdosed was described as combative descriptively. Results: Among the 211 incidents in which police responded to an overdose during the study period, we found that police administered naloxone in approximately 10% of incidents. In most incidents, police were the last group of first responders to arrive on scene (59%), and most often, naloxone was administered by others (65%). Police were significantly more likely to administer naloxone when they were the first professionals to arrive, when naloxone had not been administered by others, and when the overdose occurred in public or in a vehicle. Arrests at overdose events were rarely reported (1%), and people who overdosed were rarely (1%) documented in incident reports as being ‘combative.’ Conclusions: Considering these findings, ideally, all jurisdictions should have sufficient first responder staffing and resources to ensure a rapid response to overdose events, with police rarely or never dispatched to respond to overdoses. However, until this ideal can be achieved, any available responders should be dispatched concurrently, with police instructed to resume patrol once other professional responders arrive on scene; additionally, warrant searches of persons on scene should be prohibited

Resolving Quiescent Galaxies at z≳2: I. Search for Gravitationally Lensed Sources and Characterization of their Structure, Stellar Populations, and Line Emission

Quiescent galaxies at z ≳ 2 are compact and have weak or absent emission lines, making it difficult to spatially resolve their kinematics and stellar populations using ground-based spectroscopy. Gravitationally lensed examples provide a promising route forward, but such objects are very rare. We describe a search in the fields of 232 galaxy clusters that has uncovered five bright (H AB < 20) lensed galaxies with red near-infrared colors. These include MRG-M0138, which is the brightest lensed galaxy known in the near-infrared. Analysis of near-infrared spectra and multiband photometry confirms that all are quiescent galaxies at z = 1.95–2.64 with stellar ages of 0.5–1.4 Gyr (corresponding to formation epochs z form ≃ 3–4) and stellar masses of 10^11.6-12.8 µ^-1 Mʘ, where μ is the magnification. In three cases, we derive lens models and reconstruct the source structure; these galaxies are massive (M ≳ 10^11.10 Mʘ) and follow the mass–size relation defined by unlensed samples. In two of these three galaxies, the main structural component is an inclined disk. Weak emission lines are detected in four of five galaxies with high ratios [NII]/Hα ≃ 2–6 that are inconsistent with a star formation origin. Based on the line ratios, the Hα equivalent widths, and the distribution and kinematics of the gas, we infer that shocks are likely to be present in at least two galaxies and could be present in all of the line emitters. We speculate that these could be analogs of local galaxies in which AGN jet-driven outflows are thought to heat the interstellar medium and suppress star formation. In further papers, we will present spatially resolved measurements of the stellar populations and kinematics of this unique sample

Resolving Quiescent Galaxies at z≳2: II. Direct Measures of Rotational Support

Stellar kinematics provide insights into the masses and formation histories of galaxies. At high redshifts, spatially resolving the stellar kinematics of quiescent galaxies is challenging due to their compact sizes. Using deep near-infrared spectroscopy, we have measured the resolved stellar kinematics of four quiescent galaxies at z = 1.95–2.64, introduced in Paper I, that are gravitationally lensed by galaxy clusters. Analyses of two of these have previously been reported individually by Newman et al. and Toft et al., and for the latter, we present new observations. All four galaxies show significant rotation and can be classified as "fast rotators." In the three systems for which the lensing constraints permit a reconstruction of the source, we find that all are likely to be highly flattened (intrinsic ellipticities of ≈0.75–0.85) disk-dominated galaxies with rapid rotation speeds of V max = 290–352 km s−1 and predominantly rotational support, as indicated by the ratio (V/σ)Re = 1.7-2.3. Compared to coeval star-forming galaxies of similar mass, the quiescent galaxies have smaller V/σ. Given their high masses, Mdyn ≳ 2 x 10^11 Mⵙ, we argue that these galaxies are likely to evolve into "slow rotator" elliptical galaxies whose specific angular momentum is reduced by a factor of 5–10. This provides strong evidence for merger-driven evolution of massive galaxies after quenching. Consistent with indirect evidence from earlier morphological studies, our small but unique sample suggests that the kinematic transformations that produced round, dispersion-supported elliptical galaxies were not generally coincident with quenching. Such galaxies probably emerged later via mergers that increased their masses and sizes while also eroding their rotational support